1. Field of the Invention
This invention relates to an oil absorption retarder capable of retarding oil absorption during frying and fried foods with lowered oil contents.
2. Related Art
Fried foods, referred as to foods produced by frying, are widely favored as foods supporting the modern people""s diet. Fried foods are widely sold at, for example, fast food shop, confectionery, bakery, cake shop, lunch shop, convenience store and supermarket, with a large variety such as doughnut, fried potato, fried chicken, tempura (Japanese deep-fat fried food), and piroshki.
Although these miscellaneous foods, discriminated by their specific texture, have been accepted by many consumers, still further needs reside in improving the texture to soar the sales. It is exceptionally important for fried foods to control their oil contents in a proper range since too much oil contents will seriously ruin the texture. It is also expected to provide foods meeting needs of consumers since they tend to reduce oil intake in the recent health-oriented boom.
It is, from another aspect, needed to use oils efficiently since the oils used for producing fried foods are expensive relative to other food materials and liable to degrade. It is most strictly needed for confectionery producing factory or fast food shop, producing a huge quantity of fried foods, to yield a maximum count of fried foods with a minimum amount of the oils.
Dough, a material for fried foods, however tends to absorb an unnecessarily large amount of oil when fried, which fails to meet the above needs. It is thus strongly needed to provide means for retarding oil absorption by dough.
The present inventors aimed to meet the above needs encountered in the prior art. It is therefore an object of the present invention to provide an oil absorption retarder capable of retarding oil absorption during frying. It is another object of the present invention to provide fried foods with lowered oil contents and improved texture.
From thorough investigations to solve the above problems, the present inventors found that alginic ester has oil absorption retarding property to complete the present invention.
That is, this invention is to provide an oil absorption retarder containing alginic ester, Alginic ester used in this invention preferably has a degree of esterification of 20% or above and a viscosity of 2 cp or above in the state of 1% aqueous solution at 20xc2x0 C. The oil absorption retarder of this invention may include flour, in which alginic ester is preferably contained at a ratio of 0.01 wt % or above for 100 weight parts of flour, and more preferably at 0.01 to 3 wt %.
This invention also provides fried foods produced using the above oil absorption retarder.
Alginic ester used for the oil absorption retarder of this invention is selected from compounds having a structure in which at least a part of carboxylic groups composing the alginic acid is converted into esters. There is no particular limitation on molecular weight, structure or degree of esterification, There is also no particular limitation on ratio or sequence of xcex2-D-mannuronic acid and xcex1-L-guluronic acid, both of which can be components of alginic ester. Thus an acceptable alginic ester includes such that having all of blocks consisting of xcex2-D-mannuronic acid only, blocks consisting of xcex1-L-guluronic acid only and blocks consisting of the both, or such that having either one or two blocks.
Preferable compound relates to alginic ester with a degree of esterification of 20% or above. It is, in particular, preferable to use alginic ester with a degree of esterification of 40% or higher, more particularly, 50 to 90%. Viscosity in the state of 1% aqueous solution at 20xc2x0 C. is preferably 2 cp or above, and more preferably falls within a range between 20 and 600 cp.
Alginic ester used in this invention may be originated from natural products or from synthetic products. When obtaining it from natural products, it is preferable to extract alginic acid from seaweed or so, which is followed by esterification. In more details, brown algae rich in high-molecular-weight alginic acid is washed with, for example, dilute sulfuric acid, extracted with sodium carbonate solution, precipitated with sulfuric acid to obtain high-molecular-weight alginic acid, and then esterified according to the conventional method to obtain alginic ester. Alternatively, brown algae is washed with, for example, dilute mineral acid such as dilute sulfuric acid or dilute hydrochloric acid, extracted with alkali solution such as sodium carbonate solution, and precipitated with calcium salt such as calcium chloride to obtain calcium alginate. The calcium alginate is subsequently subject to removal of calcium by dilute mineral acid such as dilute sulfuric acid or dilute hydrochloric acid to obtain high-molecular-weight alginic acid, and the resultant alginic acid is then esterified according to the conventional method to obtain alginic ester. Low-molecular-weight alginic ester can be obtained either by esterifying high-molecular-weight alginic acid after decomposed into low-molecular-weight one, or by decomposing high-molecular-weight alginic acid after esterified. Possible methods for decomposing alginic acid into low-molecular-weight one include a method based on enzyme processing of high-molecular-weight alginic acid, a method based on reaction with sodium hypochlorite or hydrogen peroxide, a method based on thermal decomposition, and a method based on pressurized decomposition.
Alginic ester used in this invention may contain functional groups or crosslinked structure as far as desired effects will not exceedingly be interfered. The alginic ester may have a form mixed with alginic acid, alginic acid salt or other alginic acid derivatives. The oil absorption retarder may further contain other components as far as desired effects will not exceedingly be interfered.
An oil absorption retarder comprising alginic ester mixed with flour is exemplified as the one applicable to fried food containing flour as its component. In this case, alginic ester content is preferably set at 0.01 wt % or above for 100 weight parts of flour, more preferably at 0.01 to 3 wt % and still more preferably at 0.05 to 1 wt %.
The oil absorption retarder of this invention also allows organic acid salts, besides flour, to be added. Organic acid salts allowable to be added include sodium citrate, potassium citrate, calcium citrate, sodium acetate, sodium ascorbate, sodium lactate, calcium lactate, sodium sulfate, potassium sulfate, calcium sulfate, potassium carbonate, sodium carbonate, calcium carbonate and calcium glycerophosphate.
The oil absorption retarder of this invention also allows polysaccharide to be added. Polysaccharide allowable to be added include alginic acid, sodium alginate, pectin, carboxymethyl cellulose, carrageenan, guar gum, curdlan, starch, gum arabic, welan gum, cassia gum, xanthan gum, chitosan, psyllium seed gum, gellan gum, tamarind seed gum, dextran, furcellaran, pullulan and hyaluronic acid.
The oil absorption retarder of this invention also allows proteins to be added. Proteins allowable to be added include egg albumen, wheat gluten, and soybean protein.
These additional components may be added independently or in combination of a plurality of them. The additional components can properly be selected depending on the object matter to which the components are to be applied.
For fried foods using shaped dough such as instant noodle or doughnut, exemplified is a powder type oil absorption retarder comprising alginic ester mixed with flour, or a liquid-type oil absorption retarder dissolving these components into water. For fried foods such as fries, i.e. so-called xe2x80x9cFrench friesxe2x80x9d or fried potato strips, tempura, fried chicken, nugget, and American dog (sausage covered with fried dough) produced by dipping raw materials into batter or those applied with bread crumb or the like, an oil absorption retarder comprising batter added with alginic ester can be used. For fried foods such as fried potato or potato chips, produced by directly frying raw materials, alginic ester dissolved into water may be used as an oil absorption retarder through coating or the like.
There is no specific limitation on the form of the oil absorption retarder of this invention, where a variety of forms including solid, jelly, paste and liquid is allowable. It is preferable to properly select the form according to the object matter to which the oil absorption retarder is to be applied and mode of its utilization.
To offer high oil absorption retarding effects, it is preferable to use a solution in which an alginic ester is dissolved. Similarly, such high oil absorption retarding effects can be brought when a powder type alginic ester is used. The particle size of the powders in such a situation is preferably equal to or less than 125 xcexcm, more preferably, equal to or less than 110 xcexcm, and further preferably equal to or less than 100 xcexcm.
Use of the powder type alginic ester can render the retarder mixed uniformly with powder materials such as flours in a short time before use. If powder materials can be easily, uniformly prepared in advance, products can be easily manufactured with stable quality. Because the dissolving step becomes unnecessary to manufacture the oil absorption retarder where the powder type alginic ester is used, investments for facilities to do dissolution become unnecessary, so that products can be manufactured with less energy and reduced costs. Therefore, the powder type oil absorption retarder can be easily used for manufacturing in small size factories and shops, which have no dissolution facility, and also, can be used advantageously for products for home use.
A method for applying the oil absorption retarder of this invention may properly be selected according to purposes of retarding oil absorption or so. For example, the oil absorption retarder may thoroughly be mixed into the object matter so that the entire part of the object matter will have an uniform retardation effect for oil absorption, or the oil absorption retarder may concentrically be applied to the specific areas so that the final oil contents will differ by areas. It is also allowable to apply the oil absorption retarder at different concentrations to produce areas with various oil contents. In particular in the production of fried foods, areas where toppings to be applied can be designed to have controlled oil contents depending on sources of the toppings, so as to provide good taste of fried foods as a whole while retaining texture of the toppings.
The oil absorption retarder of this invention will find its most effective use in fried foods, but it may also be effective in industrial and agricultural applications besides food-related ones and may have no limitation on object matters to which the retarder is to be applied.
The oil absorption retarder of this invention exerts its effect in retarding oil absorption during frying of the object matter to which the oil absorption retarder is applied. Its effect of retarding oil absorption reaches as high as 30% or more as compared with the case without using the oil absorption retarder of this invention. This effect is ascribable to alginic ester contained in the oil absorption retarder of this invention. Accordingly, if the oil absorption retarder of the invention is used, low calorie foods can be provided with lower costs.
Use of the oil absorption retarder of this invention may further result in effects other than retarding oil absorption. It has confirmed that the oil absorption retarder of this invention used in production of noodles shows effect of preventing noodles from swelling in hot water. It is further expected that the oil absorption retarder of this invention will improve texture when applied to a wide variety of foods.